This invention relates to an electro-mechanical filter having a plurality of tuning forks, and more particularly relates to an electro-mechanical filter having a plurality of tines disposed around the perimeter of the base plate instead of being disposed in a line configuration.
Conventionally, there are many kinds of band pass filters which are made of tuning forks having close center frequencies. For example, some of these electro-mechanical filters are shown in FIG. 1.
In FIG. 1(A), plural tuning forks are made by mechanical cutting or milling. Tuning forks 1 and 2 having tines 1a, 1b and 2a, 2b are fixed in a linear row to a supporting member 3 respectively by spot welding at the base plates 1c and 2c.
Another band pass filter of duplex tuning fork configuration is shown in FIG. 1(B). Tuning forks 1 and 2 are pressed out from a sheet of thin metal plate by a pressing machine, and then the flat tuning fork blanks are formed into tuning forks by bending. Then these tuning forks are fixed in a linear row to a supporting member 4.
In these conventional filters, the plurality of tuning forks are aligned linearly in the direction of the arrow X so that a relatively long space is needed in the horizontal direction in order to contain the tuning forks.
Because of this, these electro-mechanical filters are not available for circuit elements which must be minimized in size.